# Observer ?

1. Jan 11, 2012

### jbrussell93

My first question is pertaining to Schrodinger's Cat (i know... I am still trying to grasp these concepts). So, wouldn't it make sense that the cat would be a conscious observer therefore causing wave function collapse in the first place?

My other question is just a general question about the observer. At what level of organization does a living thing STOP becoming an observer ie cell, bacteria, etc.

2. Jan 11, 2012

### Bill_K

Imagine a series of nested boxes, each containing a conscious observer. The innermost contains the cat. Each observer ascribes a wavefunction to the box he's looking at. To him, its contents are a quantum system, making no difference whether it is 'conscious' or not. The boxes are opened in sequence, starting with the innermost, revealing the outcome of the nth experiment to the nth observer, and causing the nth wavefunction to collapse. Each observer sincerely believes that his state was determined as soon as the box before him was opened. Nevertheless the remaining observers outside his box believe he's still in a superposition.

3. Jan 11, 2012

### DaveC426913

Bill K explained it well.

The closed box contains two superposed states:

1] a cat - safe from harm - that sees a collapsed state of (itself and the contents of the box)
2] a live - but doomed - cat that sees a collapsed state of (itself and the contents of the box) - which then dies

Each one cat sees a collapsed state, true but - until the box is opened - there are in essence two cats observing two states.

4. Jan 11, 2012

### jbrussell93

This would all make sense if time truly progressed asymmetrically forward. Since time is symmetric but we only "perceive" it as progressing asymmetrically forward, it would seem that once the cat in the internal box became aware (certain) of its conditions, this would become a certainty throughout all space-time instantly even though the other observers could not "perceive" it yet. Therefore, each subsequent observer is already certain before they open the box even though they cannot perceive this certainty.

I must be missing something :/

5. Jan 11, 2012

### DaveC426913

You're assuming there's only one reality. The point - to continue the analogy - is that there are multiple simultaneous potential realities.

6. Jan 11, 2012

### jbrussell93

That would only be true assuming the many worlds interpretation correct? I am assuming there is only one "reality".

The problem I have with the many worlds interpretation is that there are potentially an infinite number universes acting out an infinite number of possibilities. It seems that in math, infinite is a dead end... usually due to a lack of a deeper understanding.

Why must we require multiple simultaneous realities?